Black Toners Research Articles

Raman Spectroscopic Analysis of Inkjet and Laser Printed Documents to Find the Source of Printing

This work investigates the use of Raman spectroscopy as a non-destructive tool for analysing inkjet and laser printed counterfeits. The primary goal of the study was to determine if Raman spectroscopy is an acceptable tool for demonstrating the link between various specimens of counterfeits suspected of being printed with the same toner on the same machine. Specimens of several kinds of toners printed on various types of paper are studied using a Raman spectroscopy apparatus with an excitation line at 514.5 nm. Cyan, magenta, yellow, and black toners are examined independently for each specimen. The Raman spectra of the cyan and yellow toners were the most distinguishable. The findings reveal that Raman spectroscopy may be used effectively to analyse colour toner printed document counterfeiting, such as banknotes and papers, in order to create linkages between more or less varied specimens of counterfeits by evaluating the characteristics of a colour toner.

Laser‐induced breakdown spectroscopy and chemometric analysis of black toners for forensic applications

AbstractIn the present work, laser‐induced breakdown spectroscopy (LIBS) was used to differentiate between different black toners of printers and photocopiers based on their elemental composition. Measurements were performed on 23 toner samples of different printers and six different photocopiers (of different brands and models). The LIBS spectra were compared to characterize each toner type. Multivariate statistical analysis based on PCA and graph clustering was used to develop a discrimination model between the toners in questioned documents. Good discrimination of both brand and model toners was obtained. The results may be beneficial for forensic applications in the investigations of questioned documents.

On the spectroscopic examination of printed documents by using a field emission scanning electron microscope with energy-dispersive X-ray spectroscopy (FE-SEM-EDS) and chemometric methods: application in forensic science.

The detection of computer-generated document forgeries has always been a challenging task for forensic document examiners (FDE). With the aim to support the examination processes, Schottky field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FE-SEM-EDS) is explored as a recent tool to analyze black toners obtained from laser printers and photocopier machines. Forty samples each from the laser printer and photocopier machines are procured and studied for morphological features, elemental profile, and multivariate analysis. The acquired SEM images and spectra are evaluated to discriminate and classify the toners having a different source of origin. Multivariate analysis is applied to develop a model of classification to successfully classify the printed documents on the basis of the similarities and differences in their composition. Hierarchical cluster analysis (HCA) discriminates the printouts in the forms of groups based on their chemical composition. The laser printer and the photocopier printed documents are grouped into 11 and eight clusters, respectively, based on their elemental composition. Cross-validation is further conducted to assess the capabilities of developed principal component analysis (PCA) and linear discriminant analysis (LDA) models for the examination of printouts from unknown origin. Graphical abstract.

Assessment of the Possibility of Identification of Black Toners on Printouts in Lexmark Printers Using SEM Method.

Background:Document examiners are frequently asked to determine whether or not a printout has originated from a particular laser printer. The printer can rarely be identified unless some unique defects or irregularities of the printer are present on the printout.Aim/Objective:The project aimed at obtaining the individual identification of printing and copying devices.Material and Methods:This paper presents an overview of a systematic approach to characterizing and discriminating the toner of different laser printer cartridges using scanning electron microscopy. A total of 21 collected printouts were printed on 21 different Lexmark printing machine models. Sixteen printouts were obtained using printers with original toner cartridges, while five printouts were obtained using printers with replacements. Clear criteria were established for individual assessment.Results:Based on the SEM images and established criteria, the details of topography of the toner structure were revealed. Based on this study, the differences or similarities of toners on tested printouts were determined.Conclusion:The SEM technique can be successfully, simply, and rapidly applied to the analysis of toners on paper documents.

New insights in forensic chemistry: NIR/Chemometrics analysis of toners for questioned documents examination

Near-Infrared spectroscopy (NIRs) coupled to chemometrics was investigated for the first time as a new tool for the analysis of black toners to evaluate its application in forensic cases. Ten black toners from four manufacturers were included in this study and the acquired spectra were compared in order to differentiate toners. Multivariate statistical analysis based on Principal Component Analysis (PCA) was considered to develop a model of comparison of toners in questioned documents. Results demonstrated the capabilities of the approach NIR/Chemometrics to correctly identify toners when printed on different papers and to be not affected by the printing process. This study has shown that NIRs can be considered as a useful, fast, non-destructive tool providing the characterisation of toners in forensic caseworks.

Analysis and Evaluation of Magnetism of Black Toners on Documents Printed by Electrophotographic Systems

This paper reports on a study to assess the potential of measurements of magnetism, using a proprietary magnetic analysis system, for the routine analysis of toners on documents printed by black and white electrophotographic systems. Magnetic properties of black toners on documents printed by a number of different devices were measured and compared. Our results indicate that the analysis of magnetism is complementary to traditional methods for analysing black toners, such as FTIR. Further, we find that the analysis of magnetism is realistically applicable in closed set cases, that is when the number of potential printing devices can be clearly defined.

Analysis and evaluation of magnetism of black toners on documents printed by electrophotographic systems

This paper reports on a study to assess the potential of measurements of magnetism, using a proprietary magnetic analysis system, for the routine analysis of toners on documents printed by black and white electrophotographic systems. Magnetic properties of black toners on documents printed by a number of different devices were measured and compared. Our results indicate that the analysis of magnetism is complementary to traditional methods for analysing black toners, such as FTIR. Further, we find that the analysis of magnetism is realistically applicable in closed set cases, that is when the number of potential printing devices can be clearly defined.

Forensic application of laser-induced breakdown spectroscopy for the discrimination of questioned documents

Document examination is an important forensic discipline and the legal system regularly needs the knowledge and skills of the scientific expert when questioned documents are involved in criminal or civil matters. Amongst the many aspects of the scientific examination of documents, elemental analysis can provide useful results. In this study, the evaluation of the analytical performance of a commercially available laser-induced breakdown spectroscopy (LIBS) instrument was conducted on office papers, writing inks, inkjet inks and laser printer toners. The paper sample set analysed consisted of 33 Australian paper specimens originating from the same production plant but representing different brands and/or batches. In addition, a total of 131 ink or toner samples were examined that included black and blue ballpoint inks, black inkjet inks, and black laser printer toners originating from several manufacturing sources, models and/or batches. Results from the LIBS method were compared against those obtained using more established elemental profiling method such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). LIBS demonstrated detectable and significant differences between different batches of the same brand as well as between different brands of paper, ink and toner samples. The LIBS method provided comparable discrimination powers for the selected sample sets when compared to those obtained using LA-ICP-MS (discrimination from 99.8 and 100% of the sample pairs, depending on the sample subset under examination). LIBS is a suitable technique for the determination of elemental composition as part of a protocol for the examination of questioned documents.

Forensic analysis of printing inks using tandem Laser Induced Breakdown Spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Elemental analysis, using either LA-ICP-MS or LIBS, can be used for the chemical characterization of materials of forensic interest to discriminate between source materials originating from different sources and also for the association of materials known to originate from the same source. In this study, a tandem LIBS/LA-ICP-MS system that combines the benefits of both LIBS and LA-ICP-MS was evaluated for the characterization of samples of printing inks (toners, inkjets, intaglio and offset.). The performance of both laser sampling methods is presented. A subset of 9 black laser toners, 10 colored (CMYK) inkjet samples, 12 colored (CMYK) offset samples and 12 intaglio inks originating from different manufacturing sources were analyzed to evaluate the discrimination capability of the tandem method. These samples were selected because they presented a very similar elemental profile by LA-ICP-MS. Although typical discrimination between different ink sources is found to be >99% for a variety of inks when only LA-ICP-MS was used for the analysis, additional discrimination was achieved by combining the elemental results from the LIBS analysis to the LA-ICP-MS analysis in the tandem technique, enhancing the overall discrimination capability of the individual laser ablation methods. The LIBS measurements of the Ca, Fe, K and Si signals, in particular, improved the discrimination for this specific set of different ink samples previously shown to exhibit very similar LA-ICP-MS elemental profiles. The combination of these two techniques in a single setup resulted in better discrimination of the printing inks with two distinct fingerprint spectra, providing information from atomic/ionic emissions and isotopic composition (m/z) for each ink sample.

電界中における粒子移動を利用した反射型ディスプレイ (IV) ―2粒子移動型トナーディスプレイ―

電界中における粒子移動を利用した反射型ディスプレイ (IV) ―2粒子移動型トナーディスプレイ―

Erratum: Electronic Reflective Display using Particle Movement in Electric Field (IV) —Toner Display Based on Particle Movement of Black and White Toners— [NIHON GAZO GAKKAISHI (Journal of the Imaging Society of Japan) Vol. 53 (2014) , No. 1 pp.21-27

Erratum: Electronic Reflective Display using Particle Movement in Electric Field (IV) —Toner Display Based on Particle Movement of Black and White Toners— [NIHON GAZO GAKKAISHI (Journal of the Imaging Society of Japan) Vol. 53 (2014) , No. 1 pp.21-27

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

Detection and sourcing of counterfeit currency, examination of counterfeit security documents and determination of authenticity of medical records are examples of common forensic document investigations. In these cases, the physical and chemical composition of the ink entries can provide important information for the assessment of the authenticity of the document or for making inferences about common source. Previous results reported by our group have demonstrated that elemental analysis, using either Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) or Laser Ablation Induced Breakdown Spectroscopy (LIBS), provides an effective, practical and robust technique for the discrimination of document substrates and writing inks with minimal damage to the document. In this study, laser-based methods and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) methods were developed, optimized and validated for the forensic analysis of more complex inks such as toners and inkjets, to determine if their elemental composition can differentiate documents printed from different sources and to associate documents that originated from the same printing source. Comparison of the performance of each of these methods is presented, including the analytical figures of merit, discrimination capability and error rates. Different calibration strategies resulting in semi-quantitative and qualitative analysis, comparison methods (match criteria) and data analysis and interpretation tools were also developed. A total of 27 black laser toners originating from different manufacturing sources and/or batches were examined to evaluate the discrimination capability of each method. The results suggest that SEM-EDS offers relatively poor discrimination capability for this set (~70.7% discrimination of all the possible comparison pairs or a 29.3% type II error rate). Nonetheless, SEM-EDS can still be used as a complementary method of analysis since it has the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value.

Forensic Analysis of Laser Printed Ink by X-ray Fluorescence and Laser-Excited Plume Fluorescence

We demonstrated a minimally destructive two-tier approach for multielement forensic analysis of laser-printed ink. The printed document was first screened using a portable-X-ray fluorescence (XRF) probe. If the results were not conclusive, a laser microprobe was then deployed. The laser probe was based on a two-pulse scheme: the first laser pulse ablated a thin layer of the printed ink; the second laser pulse at 193 nm induced multianalytes in the desorbed ink to fluoresce. We analyzed four brands of black toners. The toners were printed on paper in the form of patches or letters or overprinted on another ink. The XRF probe could sort the four brands if the printed letters were larger than font 20. It could not tell the printing sequence in the case of overprints. The laser probe was more discriminatory; it could sort the toner brands and reveal the overprint sequence regardless of font size while the sampled area was not visibly different from neighboring areas even under the microscope. In terms of general analytical performance, the laser probe featured tens of micrometer lateral resolution and tens to hundreds of nm depth resolution and atto-mole mass detection limits. It could handle samples of arbitrary size and shape and was air compatible, and no sample pretreatment was necessary. It will prove useful whenever high-resolution and high sensitivity 3D elemental mapping is required.

A new online image analyzer for macrocontaminants in recycled pulps

A new image analysis-based instrument has been developed for measurement of low density and high density macrocontaminants from recycled pulp or whitewater. The unit is coupled to a pulp classifier that isolates the contaminants from pulp and concentrates them before their transfer to a specialized chamber that further separates the contaminants based on their relative density to water. The low density contaminants float on the water surface, whereas the high density macrocontaminants sink onto the settling plate, where images of both contaminant types are then captured and analysed. Through image analysis, the high density contaminants are further classified into two categories: contaminants that are whitish in color and mainly comprised of stickies are named heavy stickies, whereas contaminants that are blackish in color and comprised of black toners and dark wood components are named dirt. When operating in the online mode with autosamplers delivering the samples to the pulp classifier, the instrument provides macrocontaminant determinations every 15 min. The total count and surface area of both types of macrocontaminants per kilograms of pulp can then be sent by direct link to the mill data control system, allowing an effective follow-up of macrocontaminant changes in process pulps and waters. The unit also allows the user to view images of the contaminants. The analyzer results obtained in terms of number and area of macrocontaminants show a linear relationship with TAPPI T-277 om-07 “Macro stickies content in pulp: the ‘pick-up’ method.”

Diamond cell Fourier transform infrared spectroscopy transmittance analysis of black toners on questioned documents

This paper describes the use of a diamond cell Fourier transform infrared (FTIR) spectroscopy methodology for the analysis of black toners commercialised in Portugal. A total of one hundred and thirty-eight samples from eighteen manufacturers were analysed in transmittance mode through a diamond cell. This methodology was considered to be non-destructive as it allows the forensic analysis of the questioned documents while preserving their integrity. The questioned documents' substrate (paper sheets) has no influence on the final result. This technique shows high repeatability and intermediate precision. Spectra were organized in twenty distinct groups based on their main chemical characteristics and relative peak intensity; and a black toner infrared spectral library was developed. Spectral matches between forty-five blind samples and the database resulted in a 100% positive identification to the correct group.

Implementing statistical learning methods through Bayesian networks (Part 2): Bayesian evaluations for results of black toner analyses in forensic document examination

This paper presents and discusses the use of Bayesian procedures – introduced through the use of Bayesian networks in Part I of this series of papers – for ‘learning’ probabilities from data. The discussion will relate to a set of real data on characteristics of black toners commonly used in printing and copying devices. Particular attention is drawn to the incorporation of the proposed procedures as an integral part in probabilistic inference schemes (notably in the form of Bayesian networks) that are intended to address uncertainties related to particular propositions of interest (e.g., whether or not a sample originates from a particular source). The conceptual tenets of the proposed methodologies are presented along with aspects of their practical implementation using currently available Bayesian network software.

Ablative analysis of black and colored toners using LA‐ICP‐TOF‐MS for the forensic discrimination of photocopy and printer toners

AbstractPhotocopy and printer toners were analyzed using ICP‐TOF‐MS (inductively coupled plasma time‐of‐flight mass spectrometry) with laser ablation (LA). Isotopic analysis of black and colored toners allows identification and discrimination of covering materials from different producers. The results of 201 samples of black toners were analyzed according to the following chemometric methods: cluster analysis (CA) and principal component analysis (PCA). In addition, 23 samples of colored toners were tested. Chemometric manipulation of the elemental mass spectra obtained using the ‘Fingerprinting OptiMass 9500’ program showed an effective system for the rapid comparative analysis of unknown samples. Copyright © 2010 John Wiley & Sons, Ltd.

Effects of Triboelectrical Charge of Toners on Display Characteristics of Toner Display

Toner Display is based on an electrical movement of charged toner particles. Two types of black and white particle charged in the different electric polarity are enclosed in the air space between two transparent electrodes. The black toners are collected to the electrode by an electrostatic force across the insulting layer to display a black image. Those toners can be put to the counter electrode by applying a reverse electric field, and white solid image is displayed.The display contrast and driving voltage depend on the electrical charge of toner particle in the display cell. In this study, the triboelectric charges of particles in the display cell were measured using Q/M meter. Those charges depend on the mixture ratio of two toners. The triboelectric charging mechanism between small toner particles was discussed.

Implementing statistical learning methods through Bayesian networks. Part 1: A guide to Bayesian parameter estimation using forensic science data

As a thorough aggregation of probability and graph theory, Bayesian networks currently enjoy widespread interest as a means for studying factors that affect the coherent evaluation of scientific evidence in forensic science. Paper I of this series of papers intends to contribute to the discussion of Bayesian networks as a framework that is helpful for both illustrating and implementing statistical procedures that are commonly employed for the study of uncertainties (e.g. the estimation of unknown quantities). While the respective statistical procedures are widely described in literature, the primary aim of this paper is to offer an essentially non-technical introduction on how interested readers may use these analytical approaches – with the help of Bayesian networks – for processing their own forensic science data. Attention is mainly drawn to the structure and underlying rationale of a series of basic and context-independent network fragments that users may incorporate as building blocs while constructing larger inference models. As an example of how this may be done, the proposed concepts will be used in a second paper (Part II) for specifying graphical probability networks whose purpose is to assist forensic scientists in the evaluation of scientific evidence encountered in the context of forensic document examination (i.e. results of the analysis of black toners present on printed or copied documents).

Infrared Spectrometry in Discriminant Analysis of Laser Printer and Photocopy Toner on Questioned Documents

Differentiating between black powder toners used in laser printers and copiers can be challenging for forensic examiners. One hundred and eight samples from different types of cartridges produced by 10 manufacturers were studied using reflection-absorption infrared microscopy (R-A IR). The grouping of copy toners into distinguishable classes, achieved by visual comparison and computer-assisted spectral matching, was compared to that achieved by multivariate discriminant analysis. The FTIR spectra were classified into 15 groups. This classification served as a basis for the development of an analytical scheme for differentiating black powder toners. Obtained spectra and all the available information could be used to create a database. The results obtained confirm the multiplicity and compatibility of toners.